The Somatic Xuclei of Certain Cestodes. 
145 
Among more than 4300 nuclei examined x ) in different regions where 
active growth was taking place, I have observed one clear case of a 
prophase and six other doubtful cases of raitosis. Five of these were 
in the developing genital ducts, regarding the other two my record is 
lacking. 
Tliere is present between the different cells in Moniezia the same 
difference in stain that oecnrs in Taenia serrata and its larva. Tlie pos- 
sible meaning of such differences has beeil discussed by me in my previous 
paper and will be considered further in my aceonnt of micro-chemical 
tests on Taenia crassicollis. It may be noted here, however, that these 
differences cannot be due merely to differences in size (the cells with 
the great er thickness appearing more densely stain ed), because 1 have 
observed two adjacent cells of approximately the same thickness (as 
shown by carefnl focussing), which presented a marked difference in 
staining density. In some cases the cell bodv is not uniformly stained 
thruout, but shows densely stained granulär masses between which lie 
cvtoplasmic areas, which are but lightlv stained. That this appearance 
is due to shrinkage, and consequent unequal density in different parts 
of the same cell, is rendered improbable by the usnally even distribution 
in these masses of the darker staining granules, while in the meshes of 
the reticulum upon which they lie the hyaloplasm shows no evidence of 
shrinkage but appears similar to that of the lighter stained cells 2 ). That 
these differences in stain between different cells of the same tissue and 
between different parts of the same cell are due solely to differences in 
density of the cytoplasm is suggested by the fac-t that in those parts of 
a section where the tissue is evidentlv more compressed than in other 
parts the cells stain more densely. In these cases the differences in stain 
are probably due to differences in cvtoplasmic density, but this explan- 
ation for most cases is rendered highly improbable by my micro-chemical 
tests on Taenia crassicollis , to be discussed later, and by my observations 
on Taenia serrata (p. 150) 3 ). 
The nuclear membrane, which is usnally incomplete, is a modi- 
x ) This by no means represents the total number of nuclei examined. In order, 
however, to give some idea of the extent of my examination I have counted a number 
of nuclei in each species studied. The total number far exceeds these figures. The 
examination, moreover, includes manv sections from several worms in most of the 
species studied. 1 
2 ) In many instances there has probably been some shrinkage in the sub-cuti- 
cular cells, but I have earefully avoided such cells in this comparison. 
3 ) See also Young 1908: pp. 240 — 241, and pp. 148 — 150 of the present paper. 
Archiv f. Zellforschung. VI. 10 
